straight

Old English 'streht' was the past participle of 'streccan,' meaning to stretch or extend. Something straight had been stretched: a rope pulled taut, a road laid without turning, a body pulled upright. The word 'streccan' came into English from Proto-Germanic 'strakkjanan,' which also gave Dutch 'strak' (tight) and Old Norse 'strekkja' (to stretch). The Proto-Indo-European root behind all of them, 'strenk,' carried the meaning of tight or narrow, the feeling of something under tension.

By Middle English, 'streight' had already moved from physical tension to moral character. Chaucer used it in the 14th century to mean upright, honest, reliable. A 'straight' dealer was one who did not bend the rules. The transition was clean: what cannot be bent cannot deceive. English speakers extended the same logic to arithmetic and geometry, and by the 15th century 'straight' meant simply without deviation, whether in a line or in conduct.

The word branched into dozens of compounds and idioms by the 17th century. 'Straight-laced' (from tightly laced corset stays) meant rigidly proper. 'Straight-faced' meant expressionless. 'Straight' in card games like poker, fixed by the early 19th century, named a run of five sequential cards, none bent from the sequence. 'Straight' as an adverb ('go straight home') compressed an entire moral history into a direction: without detour, without deviation, without the bends that indicate something to hide.

The 19th century added a social sense. 'Going straight' by the 1860s meant leaving criminal life, returning to an unbent path. 'Straight' as an informal term for heterosexual appeared in American slang during the 1940s and 1950s, drawing on the same logic of conformity to expectation. The full weight of the word is visible here: stretched, taut, honest, upright, conventional. Every use traces back to the past participle of a verb for pulling something until it has no slack left.